The invention relates to an infinitely variable traction roller transmission speed control arrangement especially for use in automobiles.
For the performance of an automobile, control of engine and vehicle speed is not the only consideration. Even more important is the control of torque available at the driving wheels since this is what accounts for the vehicle's acceleration. In most internal combustion engines, the engine torque increases slightly with engine speed to about 2000-3000 rpm and then drops again while engine output however still increases. For maximum torque at the driving wheels, the engine should therefore be operated near top power output at which point however engine losses and fuel consumption are relatively high. For best fuel consumption the engine should be operated at relatively low speed and open throttle under which condition reserve torque at the driving wheels is relatively low.
An infinitely variable transmission theoretically permits the selection of any desirable operating condition. For an automobile this requires however a relatively inexpensive and reliable control arrangement which, in a transmission with hydrostatic thrust bearings and hydraulic transmission ratio control, is preferably of a hydraulic nature since pressurized hydraulic fluid is readily available in such a transmission.